Exposure control device for photographic cameras

ABSTRACT

In a camera an objective is provided which defines an optical path having an axis. The objective comprises an adjustable diaphragm arranged within a diaphragm plane, and a neutral density spot cooperating with the diaphragm to diminish light intensity in the diaphragm plane within a central range on the axis. A gate is arranged on the optical path in a plane normal to the axis and receiving light through the objective for exposure of a film having a specific spectral sensitivity. A support is provided to carry the neutral density spot and has at least an inoperative and an operative position, in the operative position the neutral density spot is arranged in a central position on the axis, and in inoperative position the neutral density spot is excentric to the axis. A control device is connected to the support to control its position, the control device having at least two positions according to the spectral composition of light used for exposure of the film, whereby with artificial light the support is in the inoperative position, with day light the support means is in operative position.

[ Jan.8,1974

[ EXPOSURE CONTROL DEVICE FOR PHOTOGRAPHIC CAMERAS [75] Inventors: JosefSchild, Vienna; Harald Wessner, Neunkirche'n, both of Austria [73]Assignees: Karl Vockenhuber; Raimund Hauser, both of Vienna, Austria[22] Filed: Dec. 11, 1972 [2 1] Appl. No.: 313,696

[30] Foreign Application Priority Data Primary Examiner-Robert P.Greiner Attorney-Ernest G. Montague [57] ABSTRACT In a camera anobjective is provided which defines an optical path having an axis. Theobjective comprises an adjustable diaphragm arranged within a diaphragmplane, and a neutral'density spot cooperating with the diaphragm todiminish light intensity in the diaphragm plane within a central rangeon the axis. A gate is arranged on the optical path in a plane normal tothe axis and receiving light through the objective for exposure of afilm having a specific spectral sensitivity. A support is provided tocarry the neutral density spot and has at least an inoperative and anoperative position, in the operative position the neutral density spotis arranged in a central position on the axis, and in'inoperativeposition the neutral density spot is excentric to the axis. A controldevice is connected to the support to control its position, the controldevice having at least two positions according to the spectralcomposition of light used for exposure of the film, whereby withartificial light the support is in the inoperative position, with daylight the support means is in operative position. i

' 9 Claims, 4 Drawing Figures EXPOSURE CONTROL DEVICE FOR PHOTOGRAPHICCAMERAS This invention relates to a camera, preferably a cinematographiccamera with a path of rays defined by a lens and a film gate, said lensbeing provided with an adjustable diaphragm cooperating with a grayfilter, whereby the gray filter is insertable into the path of rays bymeans of a control mechanism from a rest position to at least oneoperative position in dependence on the scene light.

It has proved that with a strong scene brightness there occur phenomenaof diffraction on the diaphragm adjusted to a smallest aperture. In thatway the sharpness of the image was impaired and the picture lackedbrilliancy. It has therefore been suggested as an improvement to disposethe gray filter in the path of rays of the lens, or what was moreadvantageous and saving space, to provide the lens neighboring thediaphragm with a large, punctiform so-called gray filter spotcorresponding to the diameter of the diaphragm aperture at which thephenomenon of diffraction already occured. However the disadvantageappeated that the gray filter spot remained inserted with artificiallight shots at small scene brightness. This circumstance turned out tobe a disadvantage with artificial light films and all the more with daylight films. As it is known, a conversion filter is inserted into thepath of rays of the lens upon use of day light films at artificiallight, whereby however the light intensity striking the film to beexposed is impaired. If now the gray filter spot is additionallyinserted into the path of rays, the

- scene light is the more weakened.

According to the invention it is therefore suggested with cameras asdescribed above that the control mechanism for the gray filter beoperated by an arrangement taking at least two different position independence on the spectral composition of the scene light e. g.artificial light and day lightbeing preferably controlled by anilluminating system disposed on the lamp squash and attached to thecamera. The control mechanism for the gray filter is expediently sooperated that it moves the filter into the path of rays at day light andmoves it out of the path of raysat artificial light. Certainly it isknown to control a filter from the lamp squash of an illuminating systemand to insert it into the path of rays. But these filters are alwaysconversion filters, which serve, as already stated, to make photographswith artificial light films at day light or with day light films atartificial light, respectively. It is also known to control the filterby means of an operating key actuated by hand, which is movable to aposition for day light or to a position for artificial light,respectively, in dependence on the scene light used.

As it is known, films with. different speed are available in thetrade..Upon use of films with a-low speed the insertion of a gray'filterinto'the path ofrays would not be necessary, as under circumstances thealready worse image quality compared to films with a higher speed wouldstill be more impaired. According to an advanced development of theinvention, it is therefore suggested that in a camera, preferablyprovided with an adjusting device for the film speed controlled by a catridge scanner, the gray filter be displaceable upon actuation of thecontrol mechanism to two different positions by the adjusting device forthe film speed, of which one position corresponding to the lower filmspeed is extra-axial preferably outside the path of rays, whereas theother position corresponding to the higher film speed is disposed withinthe path of rays.

As mentioned above, it is necessary to adapt photographs with day lightfilms at artificial light and photographs with artificial light films atday light, respectively, to the light conditions at disposal. Thisadaptation results from the insertion of a conversion filter into thepath of rays. An advantageous embodiment of the invention is to connecta support for the conversion filter with the control mechanism for thegray filter. Upon use of artificial light films however it has provedthat at light conditions corresponding to day light the conversionfilter as well as the gray filter are moved into the path of rays.According to the invention it is therefore suggested that upon use ofartificial light films, the gray filter be provided on the conversionfilter as gray filter spot being movable with the same into the path ofrays.

Further details and features of the invention will become apparent fromthe specification of the embodiments schematically illustrated in thedrawing.

FIG. 1 shows an inventive arrangement in a camera, which is adapted forthe use of super-8 films.

FIG. 2 shows a plan view of the arrangement shown in FIG. 1. I

FIG. 3 illustrates schematically how a filter support could be designedupon use of day light films.

" FIG. 4 shows schematically the design of the arrangement in a cameraillustrated in FIGS. 1 and 2.

In a camera for super-8 films, not particularly shown in FIG. 1, adiaphragm vane 4 is arranged in the path of rays of a main lens 1 and afront lens attachment 2, situated between both of them, and controlledby a galvanometer, for instance, or a diaphragm adjusting motor 3. Thelight beam emanated by the object to be taken is confined by thediaphragm vane 4 and a mask 5 forming the diaphragm aperture togetherwith the vane 4. A filter support 7 behind the diaphragm 4, 5, seen inthe direction of the incident light, being pivotally arranged about anaxis 6, bears a conversion filter 8. The arm of the filter support 7bearing the filter 8 is biased by a thigh spring 9 in clockwise sense,so that the filter is moved into the path of rays of the lens. The otherarm of the filter support 7 extends into a slot 10 arranged on thecamera casing for an illuminating system 15. Finally there is a feelerslider 12 abutting the arm of the filter support 7, which bears thefilter 8, said feeler slider 12 showing in the range of the filtersupport 7 a slope 1 1 and extending into the cartridge housing of thecamera. I

If now a super-8 cartridge 13 with a low speed film is inserted into thecamera, the cartridge 13 shows no recess in the range where the feelerslider 12 abuts (see FIG. 2). If the photograph is made at sufficientlight intensity, for instance at sun'light, the insertion of aconversion-filter is necessarywith super-8 films, as these films areartificial light films. Since however the thigh spring 9 holds thefilter 8 in the path of rays of the lens, no further manipulations arerequired. As the photograph is made with a low speed film, the feelerslider 12 elastically-abutting the cartridge 13 is displaced in thedirection of the optical axis so far, until the slope 11 comes out ofthe range of the arm of the filter support 7 bearing the conversionfilter 8. According to the invention it has been suggested to providethe conversion filter'itself with a neutral'density spot with artificiallight films. In that the slope 11 has been removed from the range of thefilter support 7, the spring 9 deviates the filter support 7 inclockwise sense, related to FIG. 1, so that the neutral density spot onthe conversion filter 8 comes to lie behind the mask and therewith intothe operating position III, where it is removed from the optical path ofrays.

In cartridges with high speed films a recess 16 in the cartridge walllies opposite the feeler slider 12, so that the slope 11 comes into therange of the filter support .7 and causes a deviation of the same incounterclockwise sense. The neutral density spot 14 takes the operatingposition II and is therewith inserted into the path of rays of the lens.

With insufficient light conditions artificial light has to be used andwith super-8 films the conversion filter has to be removed from the pathof rays. The device indicating the scene light at disposal is formedaccording to FIG. 1 by an illuminating system 15 disposed in the lampsquash. Upon insertion of the lamp squash 15 into the. slot providedtherefor in the cartridge, the squash presses the arm of the filtersupport 7 downwards against the force of a spring 9, related to FIG. 1.In that way the conversion filter 8 with the neutral density spot 14reaches the rest position I, in which the filter 8 as well as theneutral density spot 14 which with photographs at artificial light orsimilar light conditions has to be removed from the path of rays of thelens become ineffective as to the influence on the scene light.

FIG. 3 shows only schematically how a filter support 7 has to beequipped for the use of a day light film. For the exposure of a daylight film it is necessary, as already stated, to insert a conversionfilter into the path of rays of the lens for shots with artificiallight, whereby on account of the relatively small lightintensity, theneutral density spot is kept outside the path of rays. The filtersupport 7a could then take the position illustrated in FIG. 3. Withshots at day light the filter support 7a would then be deviated incounterclockwise sense, whereby in dependence on the film speed eitherthe neutral density spot 14a is inserted into the path of rays of thelens 17 (high speed films), or also it is removed from the path of rays17 (low speed films).

Finally it may be mentioned that the device indicating the scene lightat disposal must not only be formed by the lamp squash. The operatingarrangement for the neutral density spot could for instance also becontrolled by a known meter for measureing the spectral composition oflight.

In the illustrated embodiment the diaphragm cooperates with the mask,behind which the neutral density spot 14 is arranged at low film speed.With diaphragm systems without such a mask it may suffice to adjust theneutral density spot 14 excentrically to the optical axis.

What is claimed .is:

1. In a camera an objective defining an optical path having an axis,said objective comprising an adjustable diaphragm arranged within adiaphragm plane, and a neutral density spot cooperating with saiddiaphragm to diminish light intensity in said diaphragm plane within'acentral range on said axis;

gate means arranged on said optical path in a plane normal to said axisand receiving light through said objective for exposure of a film havinga specific spectral sensitivity; 1

support means to carry said neutral density spot and having at least aninoperative and an operative position, in operative position saidneutral density spot being arranged in a central position on said axis,in inoperative position said neutral density spot being excentric tosaid axis; control means connected to said support means to control itsposition, said control means having at least two positions according tothe spectral corn- 0 whereby with artificial light said support meansbeing in said inoperative position, with day light said support meansbeing in operative position.

2. A camera as set forth in claim 1, wherein saidcontrol means compriseholding means for receiving an artificial light source and sensor meansfor sensing whether said light source is connected to the camera by saidholding means.

3. A camera as set forth in claim 1, further comprising a conversionfilter for adapting light entering through said objective for thespectral sensitivity of said film, said conversion filter having atleast an operative and an inoperative position, in operative positionsaid conversion filter being inserted into said optical path, ininoperative position said filter being out of said path; said controlmeans also being connected to said conversion filter for controlling itsposition.

4. A camera as set forth in claim 3 and adapted to expose artificiallight films, wherein said neutral density spot is arranged on saidconversion filter itself.

5. In a camera an objective defining an optical path having an axis,said objective comprising an adjustable diaphragm arranged within adiaphragm plane, and a neutral density spot cooperating with saiddiaphragm to diminish light intensity in said diaphragm plane within acentral range on said axis;

gate means arranged on said optical path in a plane normal to said axisand receiving light through said objective for exposure of a film havinga specific spectral sensitivity;

support means to carry said neutral density spot and having at least oneinoperative and an operative postion, in operative position said neutraldensity spot being arranged in a central position on said axis, ininoperative position said neutral density spot being excentric to saidaxis;

first control means connected to said support means to control itsposition, said first control means having at least one positioncorresponding to day light and one position corresponding to artificiallight, and being operable in accordance with the spectral composition oflight used for exposure; second control means connected to said supportmeans to control its position, said second control means having at leastone position corresponding to a lower range of film speed and oneposition correspodning to a higher range of film speed;

said support means being in operative position only with said firstcontrol means being in day light position and said second control meansbeing in its higher range of film speed position.

6. A camera as set forth in claim 5, wherein said support means have atleast two inoperative positions, one of which corresponding to'theartificial light position of said first control means, the other onecorresponding to the-day light position of said first control meansand'to position of light used for exposure of said film,

the lower range of film speed position of said second control means.

7. In a camera an objective defining an optical path having an axis,said objective comprising an adjustable diaphragm arranged within adiaphragm plane,

and a neutral density spot cooperating'with said diaphragm to diminishlight intensity in said diaphragm plane within a central range on saidaxis;

gate means arranged on said optical path in a plane normal to said axisand receiving light through said objective for exposure of a film havinga specific spectral sensitivity;

means for receiving a film cartridge containing said film and havingfilm speed signaling means, said cartridge receiving means being locatedbehind said gate means with respect to said objective;

support means to carry said neutral vdensity spot and having at leastone inoperative and an operative position, in operative position saidneutral density spot being arranged in a central position on said axis,in inoperative position said neutral density spot being excentric tosaid axis;

first control means connected to said support means to control itsposition, said first control means having at least one positioncorresponding to day light and one position corresponding to artificiallight, and being operable in accordance with the spectral composition oflight used for exposure;

second control means connected to said support means to control itsposition, said second control means having at least one positioncorresponding to a lower range of film speed and one positioncorresponding to a higher range of film speed, wherein said secondcontrol means include feeler means to cooperate with said film speedsignaling means of said cartridge for determing the position of saidsecond control means;

said support means being in operative position only with said firstcontrol means being in day light position and said second control meansbeing in its higher range of film speed position.

8. A camera as set forth in claim 7 further comprising spring meansurging said second control means into the position corresponding to thelower range of film speed, said second control means being movable intoits higher range of film speed position by said feeler means againstsaid spring means.

9. A camera as set forth in claim 7, wherein said feeler means areconnected with at least one oblique control surface extending inmoving'direction of said feeler means, said support means being movablein a plane normal to the moving direction of said feeler means and beingbiased towards said control surface and abutting the same.

1. In a camera an objective defining an optical path having an axis,said objective comprising an adjustable diaphragm arranged within adiaphragm plane, and a neutral density spot cooperating with saiddiaphragm to diminish light intensitY in said diaphragm plane within acentral range on said axis; gate means arranged on said optical path ina plane normal to said axis and receiving light through said objectivefor exposure of a film having a specific spectral sensitivity; supportmeans to carry said neutral density spot and having at least aninoperative and an operative position, in operative position saidneutral density spot being arranged in a central position on said axis,in inoperative position said neutral density spot being excentric tosaid axis; control means connected to said support means to control itsposition, said control means having at least two positions according tothe spectral composition of light used for exposure of said film,whereby with artificial light said support means being in saidinoperative position, with day light said support means being inoperative position.
 2. A camera as set forth in claim 1, wherein saidcontrol means comprise holding means for receiving an artificial lightsource and sensor means for sensing whether said light source isconnected to the camera by said holding means.
 3. A camera as set forthin claim 1, further comprising a conversion filter for adapting lightentering through said objective for the spectral sensitivity of saidfilm, said conversion filter having at least an operative and aninoperative position, in operative position said conversion filter beinginserted into said optical path, in inoperative position said filterbeing out of said path; said control means also being connected to saidconversion filter for controlling its position.
 4. A camera as set forthin claim 3 and adapted to expose artificial light films, wherein saidneutral density spot is arranged on said conversion filter itself.
 5. Ina camera an objective defining an optical path having an axis, saidobjective comprising an adjustable diaphragm arranged within a diaphragmplane, and a neutral density spot cooperating with said diaphragm todiminish light intensity in said diaphragm plane within a central rangeon said axis; gate means arranged on said optical path in a plane normalto said axis and receiving light through said objective for exposure ofa film having a specific spectral sensitivity; support means to carrysaid neutral density spot and having at least one inoperative and anoperative postion, in operative position said neutral density spot beingarranged in a central position on said axis, in inoperative positionsaid neutral density spot being excentric to said axis; first controlmeans connected to said support means to control its position, saidfirst control means having at least one position corresponding to daylight and one position corresponding to artificial light, and beingoperable in accordance with the spectral composition of light used forexposure; second control means connected to said support means tocontrol its position, said second control means having at least oneposition corresponding to a lower range of film speed and one positioncorrespodning to a higher range of film speed; said support means beingin operative position only with said first control means being in daylight position and said second control means being in its higher rangeof film speed position.
 6. A camera as set forth in claim 5, whereinsaid support means have at least two inoperative positions, one of whichcorresponding to the artificial light position of said first controlmeans, the other one corresponding to the day light position of saidfirst control means and to the lower range of film speed position ofsaid second control means.
 7. In a camera an objective defining anoptical path having an axis, said objective comprising an adjustablediaphragm arranged within a diaphragm plane, and a neutral density spotcooperating with said diaphragm to diminish light intensity in saiddiaphragm plane within a central range on said axis; gate means arrangedon said optical path in a Plane normal to said axis and receiving lightthrough said objective for exposure of a film having a specific spectralsensitivity; means for receiving a film cartridge containing said filmand having film speed signaling means, said cartridge receiving meansbeing located behind said gate means with respect to said objective;support means to carry said neutral density spot and having at least oneinoperative and an operative position, in operative position saidneutral density spot being arranged in a central position on said axis,in inoperative position said neutral density spot being excentric tosaid axis; first control means connected to said support means tocontrol its position, said first control means having at least oneposition corresponding to day light and one position corresponding toartificial light, and being operable in accordance with the spectralcomposition of light used for exposure; second control means connectedto said support means to control its position, said second control meanshaving at least one position corresponding to a lower range of filmspeed and one position corresponding to a higher range of film speed,wherein said second control means include feeler means to cooperate withsaid film speed signaling means of said cartridge for determing theposition of said second control means; said support means being inoperative position only with said first control means being in day lightposition and said second control means being in its higher range of filmspeed position.
 8. A camera as set forth in claim 7 further comprisingspring means urging said second control means into the positioncorresponding to the lower range of film speed, said second controlmeans being movable into its higher range of film speed position by saidfeeler means against said spring means.
 9. A camera as set forth inclaim 7, wherein said feeler means are connected with at least oneoblique control surface extending in moving direction of said feelermeans, said support means being movable in a plane normal to the movingdirection of said feeler means and being biased towards said controlsurface and abutting the same.